66% or better

Programmable AVR thermostat

This nifty thermostat is actually built from just a few off the shelf components. A Dallas DS1820 1-wire temperature sensor provides and an Olimex ATMega development board. If you’re not so handy with the soldering side, you can pull this one off. The device can be programmed by the button cluster and will even output status via the serial port.


  1. Michael Witt says:

    ‘olimex’ not olimax.

  2. I’ve wanted to see a thermostat project for a while, so I thank you for that… but this seems to be needlessly cumbersome. I also would have appreciated if they designed to run on batteries like every other digital thermostat on the market. The option of a power adapter is nice but most homes are wired for a mechanical thermostat meaning that power likely isn’t available.

  3. Tom says:

    Well, if all you’re looking for is an analog thermostat, here’s a thermostat relay done in what looks like a pretty minimal circuit.

    A site I have a lot of fun browsing now and then happens to have a rather low-effort electronic thermometer, one using 2 components and a cheap digital multimeter:

    This site (sorry, it’s got ads)
    …has an article originally written in 1993 doing more or less the same thing with older (and more) components which one of the fellows from the parts manufacturer for the IC they mentioned updated.
    The updated portion has a rather black-box solution using three ICs and a little LCD display. Not very hacky, considering the components involved, but it’s still a digital thermometer, and apparently the chip supplier (Analog Devices) gives samples. Can’t beat free.

    The microcontroller solution in the story may be a bit of overkill, but let’s face it, if you’ve already bought one (for school or for fun) then you’re probably itching for fun stuff to do with it. This is one of those fun things.

  4. Dan P says:

    No kidding, I’m in the middle of developing an AVR-based thermostat for a saltwater fishtank. Small world, eh?

  5. amk says:

    neat. i’ve been thinking about doing something like this. mainly i’d like to be able to adjust the thermostat from the laptop upstairs instead of walking down two floors in the middle of the night. i’m lazy.

  6. Jaime says:

    $100 just for a thermostat? Just buy an HAI RC-80 for $150 http://www.iautomate.com/rc80.html and get a nice looking battery operaterated thermostat with a serial port. I would get excited over a $30 project thermostat with an ethernet port.

  7. Steve says:

    {Bleah} For lack of a better feeling. You want to program a thermostat? Get a honeywell low end (not the round type) Anyway they have an Atmega inside with easy access to the programming isp pins. Even the more elite line of vision pro use atmega.

    A word of caution though, if you plan to use this in your home you better damn well understand heat anticipation and the practical implementations of such algorithms or you will likely waste alot of money in fuel or electric.

  8. aficionado says:

    A word of caution though, if you plan to use this in your home you better damn well understand heat anticipation and the practical implementations of such algorithms or you will likely waste alot of money in fuel or electric.

    this can not be stressed enough

  9. The One True Stickman says:

    twistedsymphony (and anyone else who wonders): All normal thermostat systems use 24V power. The ground isn’t always wired in home installations, though, which complicates things. If your system does have a ground wired in you can power the thermostat from it without too much trouble; otherwise, you could run new wire.

    online Reference: http://highperformancehvac.com/thermostat-wiring-colors.html

  10. anonymous says:

    Please for the love of god, HackaDay, PLEASE put in a system allowing account holders to report comment spam.

    It is oretty darn obvious that the above 2 comments (Harry, Nicholas) should either have been blocked, or promptly removed.

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